Abstract

Single crystals of a new compound, BaBi{sub 2}B{sub 4}O{sub 10} were grown by cooling a melt with the stoichiometric composition. The crystal structure of the compound has been solved by direct methods and refined to R {sub 1}=0.049 (wR=0.113) on the basis of 1813 unique observed reflections (|F {sub o}|>4{sigma}|F {sub o}|). It is monoclinic, space group P2{sub 1}/c, a=10.150(2), b=6. 362(1), c=12.485(2) A, {beta}=102.87(1){sup o}, V=786.0(2) A{sup 3}, Z=4. The structure is based upon anionic thick layers that are parallel to (001). The layers can be described as built from alternating novel borate [B{sub 4}O{sub 10}]{sup 8-} {sub {infinity}} chains and bismuthate [Bi{sub 2}O{sub 5}]{sup 4-} {sub {infinity}} chains extended along b-axis. The borate chains are composed of [B{sub 3}O{sub 8}]{sup 7-} triborate groups of three tetrahedra and single triangles with a [BO{sub 2}]{sup -} radical. The borate chains are interleaved along the c-axis with rows of the Ba{sup 2+} cations so that the Ba atoms are located within the layers. The layers are connected by two nonequivalent Ba-O bonds as well as by two equivalent Bi-O bonds with bond valences in the range of 0.2-0.3 v.u. Thermal expansion of BaBi{sub 2}B{sub 4}O{sub 10} studied by high-temperature X-ray powdermore » diffraction in the temperature range of 20-700 deg. C (temperature step 30-35 deg. C) is highly anisotropic. While the b and c unit-cell parameters increase almost linearly on heating, temperature dependencies of a parameter and {beta} monoclinic angle show nonlinear behavior. As a result, on heating orientation of thermal expansion tensor changes, and bulk thermal expansion increases from 20x10{sup -6} deg. C{sup -1} at the first heating stage up to 57x10{sup -6} deg. C{sup -1} at 700 deg. C that can be attributed to the increase of thermal mobility of heavy Bi{sup 3+} and Ba{sup 2+} cations. - Graphical abstract: New borate and bismuthate one-dimensional polyions.« less

@article{osti_21015689,
title = {Preparation, crystal structure and thermal expansion of a new bismuth barium borate, BaBi{sub 2}B{sub 4}O{sub 10}},
author = {Bubnova, R.S. and Krivovichev, S.V. and Filatov, S.K. and Egorysheva, A.V. and Kargin, Y.F.},
abstractNote = {Single crystals of a new compound, BaBi{sub 2}B{sub 4}O{sub 10} were grown by cooling a melt with the stoichiometric composition. The crystal structure of the compound has been solved by direct methods and refined to R {sub 1}=0.049 (wR=0.113) on the basis of 1813 unique observed reflections (|F {sub o}|>4{sigma}|F {sub o}|). It is monoclinic, space group P2{sub 1}/c, a=10.150(2), b=6. 362(1), c=12.485(2) A, {beta}=102.87(1){sup o}, V=786.0(2) A{sup 3}, Z=4. The structure is based upon anionic thick layers that are parallel to (001). The layers can be described as built from alternating novel borate [B{sub 4}O{sub 10}]{sup 8-} {sub {infinity}} chains and bismuthate [Bi{sub 2}O{sub 5}]{sup 4-} {sub {infinity}} chains extended along b-axis. The borate chains are composed of [B{sub 3}O{sub 8}]{sup 7-} triborate groups of three tetrahedra and single triangles with a [BO{sub 2}]{sup -} radical. The borate chains are interleaved along the c-axis with rows of the Ba{sup 2+} cations so that the Ba atoms are located within the layers. The layers are connected by two nonequivalent Ba-O bonds as well as by two equivalent Bi-O bonds with bond valences in the range of 0.2-0.3 v.u. Thermal expansion of BaBi{sub 2}B{sub 4}O{sub 10} studied by high-temperature X-ray powder diffraction in the temperature range of 20-700 deg. C (temperature step 30-35 deg. C) is highly anisotropic. While the b and c unit-cell parameters increase almost linearly on heating, temperature dependencies of a parameter and {beta} monoclinic angle show nonlinear behavior. As a result, on heating orientation of thermal expansion tensor changes, and bulk thermal expansion increases from 20x10{sup -6} deg. C{sup -1} at the first heating stage up to 57x10{sup -6} deg. C{sup -1} at 700 deg. C that can be attributed to the increase of thermal mobility of heavy Bi{sup 3+} and Ba{sup 2+} cations. - Graphical abstract: New borate and bismuthate one-dimensional polyions.},
doi = {10.1016/j.jssc.2006.11.001},
journal = {Journal of Solid State Chemistry},
number = 2,
volume = 180,
place = {United States},
year = {Thu Feb 15 00:00:00 EST 2007},
month = {Thu Feb 15 00:00:00 EST 2007}
}

Single crystals of a new compound, Ba{sub 2}Bi{sub 3}B{sub 25}O{sub 44}, were grown by cooling a melt of non-stoichiometric composition. The crystal structure was solved by direct methods and refined to R=0.030 (wR=0.090). The compound is trigonal, R3{sup Macron }m, a=7.851(2), c=46.20(1) A, V=2466.6(6) A{sup 3}, Z=3. The structure is based upon a borate layered anion of the type not previously observed in inorganic compounds. The layer consists of three sublayers; it is {approx}13 A thick and oriented parallel to (001). Two of the sublayers are built from triborate groups, [B{sub 3}O{sub 8}]{sup 7-}, whereas the central sublayer consists ofmore » triborate groups, [B{sub 3}O{sub 6}]{sup 3-}. The interlayer space is occupied by the Bi{sup 3+} ions in octahedral coordination. The Ba{sup 2+} cations are located in the cavities within borate layer. The single-phase polycrystalline sample of Ba{sub 2}Bi{sub 3}B{sub 25}O{sub 44} prepared by solid-state reactions from a stoichiometric mixture has been investigated by high-temperature X-ray powder diffraction in air. Anisotropic character of the thermal expansion is not typical for layered structures: {alpha}{sub a}=12, {alpha}{sub c}=6, {alpha}{sub V}=30 Multiplication-Sign 10{sup -6} Degree-Sign S{sup -1} at 25 Degree-Sign S; anisotropy increases on heating: {alpha}{sub a}=12, {alpha}{sub c}=0, {alpha}{sub V}=24 Multiplication-Sign 10{sup -6} Degree-Sign S{sup -1} at 700 Degree-Sign S. - Graphical abstract: Correlation between the pole figure of the thermal expansion coefficients and the structure of Ba{sub 2}Bi{sub 3}B{sub 25}O{sub 44} projected onto ac plane. The pole figures are presented for room temperature and 700 Degree-Sign C. Highlights: Black-Right-Pointing-Pointer A novel borate Ba{sub 2}Bi{sub 3}B{sub 25}O{sub 44} has been synthesized by cooling a non-stoichiometric melt. Black-Right-Pointing-Pointer The crystal structure is based upon a novel borate layered anion ({approx}13 A thick). Black-Right-Pointing-Pointer Anisotropy of thermal expansion increases on heating. Black-Right-Pointing-Pointer Anisotropy dictated by the orientation of triborate groups.« less

A new gadolinium fluoride borate Gd{sub 4}B{sub 4}O{sub 11}F{sub 2} was yielded in a Walker-type multianvil apparatus at 7.5 GPa and 1100 deg. C. Gd{sub 4}B{sub 4}O{sub 11}F{sub 2} crystallizes monoclinically in the space group C2/c with the lattice parameters a=1361.3(3) pm, b=464.2(2) pm, c=1374.1(3) pm, and beta=91.32(3){sup o} (Z=4). The crystal structure exhibits a structural motif not yet reported from borate chemistry: two BO{sub 4}-tetrahedra (square) and two BO{sub 3}-groups (DELTA) are connected via common corners, leading to the fundamental building block 2DELTA2square:DELTAsquaresquareDELTA. In the two crystallographically identical BO{sub 4}-tetrahedra, a distortion resulting in a very long B-O-bond ismore » found. - Graphical abstract: A new gadolinium fluoride borate Gd{sub 4}B{sub 4}O{sub 11}F{sub 2} could be synthesized via high-pressure/high-temperature synthesis (multianvil technique). The crystal structure exhibits a structural motif not yet reported from borate chemistry: two BO{sub 4}-tetrahedra (square) and two BO{sub 3}-groups (DELTA) are connected via common corners, leading to the fundamental building block 2DELTA2square:DELTAsquaresquareDELTA.« less

Single crystals of alpha- and beta-polymorphs of Bi{sub 2}B{sub 8}O{sub 15} were grown by Czochralski method from a charge of the stoichiometric composition. The crystal structure of beta-Bi{sub 2}B{sub 8}O{sub 15} was solved by direct methods from a twinned crystal and refined to R1=0.081 (wR=0.198) on the basis of 1584 unique observed reflections (I>2sigma(I)). The compound is triclinic, space group P1-bar, a=4.3159(8), b=6. 4604(12), c=22.485(4) A, alpha=87.094(15){sup o}, beta=86.538(15){sup o}, gamma=74.420(14){sup o}, V=602.40(19) A{sup 3}, Z=2. The B-O layered anion of beta-Bi{sub 2}B{sub 8}O{sub 15} is topologically identical to the anion of alpha-Bi{sub 2}B{sub 8}O{sub 15} but the orientation ofmore » neighboring layers is different. Thermal expansion of alpha-Bi{sub 2}B{sub 8}O{sub 15} has been investigated by X-ray powder diffraction in air in temperature range from 20 to 700 deg. C. It is strongly anisotropic, which can be explained by the hinge mechanism applied to chains of Bi-O polyhedra. While the anisotropy of thermal expansion is rather high, the volume thermal expansion coefficient alpha{sub V}=40x10{sup 6} deg. C{sup -1} for alpha-Bi{sub 2}B{sub 8}O{sub 15} is close to those of other bismuth borates. - Graphical abstract: Typical Bi{sub 2}O{sub 2} unit in crystal structure of alpha- and beta-Bi{sub 2}B{sub 8}O{sub 15}.« less